They’ve called him a liar, a clown, and the possible death of the Republican Party.

But now, as Donald Trump notches another big victory in the GOP presidential primary, the Republicans who once steadfastly opposed his campaign are contemplating a different name for him: our nominee.

[Related: Cruz Unloads on Trump Ahead of Indiana Primary] Trump’s march to the nomination, underscored again by Tuesday’s commanding victory in Indiana and Ted Cruz's exit from the race, has divided the loose coalition of Republican and conservative leaders who for months have fought his campaign.

At the heart of their split is whether continued attacks against the New York billionaire will only weaken the party’s inevitable nominee further – or whether Trump’s polarizing candidacy necessitates that his foes continue their fight no matter the long odds.

And late Tuesday in tweet, Republican National Committee Chair Reince Priebus referred to Trump as the "presumptive GOP nominee" and said the party needed to be "united and focus on defeating Hillary Clinton."

More Republican voters have apparently come around to the idea: A CNN/ORC poll released Monday found 89 percent of them think Trump will be the party’s presidential nominee.

What was once a war within the Republican Party may be all but over.

“People have to realize that Trump played by the rules. The people spoke. And at some point, it’s time to move on and worry about winning in November,” said John Brabender, who was a senior adviser to both of Rick Santorum’s presidential campaigns. “This effort to oppose Trump, regardless of what voters are saying, is absurd.”

The Inevitable Nominee?

Trump portrays himself as the inevitable nominee, arguing that the party needs to unite ahead of a likely match-up with Hillary Clinton.

A presidential front-runner making the case that their rivals need to drop out of the race is a common tactic near the end of the primary — and, in fact, it’s an argument Clinton is making against Bernie Sanders as their race winds down.

The candidate and their allies usually argue that the party needs more time to heal while the nominee redirects their attacks and gears up their fundraising operation for the general election.

But to some Republicans, that argument doesn’t apply to Trump. Their pushback is rooted in part in politics: Some hold out hope that a Trump nomination can be averted by late primaries in Nebraska and California.

For a general election, meanwhile, many Republicans fear that a disastrous Trump campaign atop this year’s ticket could deliver both the Senate and House back to Democrats.

But the need to keep fighting the GOP front-runner is also moral, says Tim Miller, an adviser to the anti-Trump group Our Principles PAC.

Trump is simply not fit to be president, he said, citing the candidate’s comments Tuesday linking Ted Cruz’s father to the assassination of former President John F. Kennedy.

“My question to the people who want to unite behind him is, where is the line?” Miller asked. “If you’re going to unite behind Donald Trump, who wouldn’t you unite behind? It’s hard for me to understand the get–in-line crowd when the line is being led by someone like Donald Trump.”

Miller isn’t alone in his dissent. The Weekly Standard, responding to the Journal's editorial, retorted that no matter the political circumstances, Trump “should not be the president of the United States.”

Still, it’s unclear how much longer anti-Trump efforts will continue. The Club for Growth, which has spent about $11 million attacking Trump, will hold a regularly scheduled meeting for its Super PAC on Wednesday to discuss, among other topics, the group’s approach to the GOP presidential primary, according to a spokesman.

And even if Miller’s group, Our Principles PAC has its heart in the fight, Republicans question whether it can persuade donors to pony up for a cause many of them might now regard as hopeless.

Trump's Difficult Task

Whether the party fully unites behind Trump could also depend on the actions of the candidate himself.

Leading GOP strategists acknowledge that Trump will face a difficult task to bring the GOP together after he alienated many of its voters and leaders.

But he can assuage those concerns by making a series of high-profile moves, including naming the man or woman he would nominate to fill the vacant slot on the Supreme Court, said Brad Todd, a Republican operative. That would be an unusual step for a presidential nominee to take, but one the strategist said might be necessary if the party is to rally behind Trump.

Trump needs to "take areas where Republicans question his commitment to our ideology and flesh out what a Trump presidency would mean,” Todd said.